An adaptive movable polymer gel profile control agent, and a preparation method and application thereof

Abstract

The application discloses a self-adaptive movable polymer gel profile control agent and a preparation method and application thereof. The preparation method comprises the following steps: mixing methylacryloylpropyltrimethylammonium chloride, dimethyldiallylammonium chloride, acrylamide, methylene bisacrylamide and water, adding an initiator, and performing polymerization reaction to obtain polymer A; mixing 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, acrylamide, methylene bisacrylamide and water, adjusting the pH value of the system to neutral, adding an initiator, and performing polymerization reaction to obtain polymer B; crushing and mixing the polymer A and the polymer B, soaking in a stabilizer, and processing through a colloid mill to obtain a gel dispersion liquid; and adding a crosslinking agent and an additive into the obtained gel dispersion liquid to obtain the polymer gel profile control agent. The gel profile control agent has good self-adaptive mobility, shear resistance, temperature resistance and salt resistance, and can be used in high-water-content oil fields, fault block oil fields, offshore oil fields and the like to improve the recovery rate.

Description

Technical Field

[0001] This invention belongs to the field of oilfield development technology, specifically relating to an adaptive mobile polymer gel profile control agent, its preparation method, and its application. Background Technology

[0002] The recovery rate of an oilfield is determined by the efficiency of the injected fluid, which is reflected in the swept volume and oil washing efficiency. The complexity of the formation (such as heterogeneity) and the large water flow channels formed by long-term water injection result in a small swept volume of injected water and a low recovery rate. In the high and ultra-high water-cut stages of the later stages of production, a large amount of injected water flows through the reservoir, leaving the medium and low permeability layers untouched and with a large amount of residual oil remaining. At this time, profile control throughout the entire process to change the direction of injected water seepage and increase the swept volume of injected water is an important method to improve oil displacement efficiency.

[0003] In recent years, the main technological measures adopted to improve swept volume have been stratified water injection and profile control. Due to the significant limitations of stratified water injection, profile control is currently the more widely used method. Existing profile control methods mainly include inorganic particulate plugging agents, pre-crosslinked bulking agents, and crosslinked polymer gels. However, current inorganic particulate profile control agents, due to their large particle size, often only have a plugging effect on the oil layer near the water well, and water quickly flows around and re-enters the high-permeability layer. Crosslinked polymer gels, on the other hand, have a strong binding effect on residual oil, and after subsequent water injection breaks through the gel layer, the resistance to water is significantly reduced, shortening the effective period. These profile control methods mainly improve the seepage conditions near the water injection well, increasing only the swept volume of the formation near the water injection well. However, the residual oil saturation near the water injection well is often low, having little impact on improving oil recovery. Therefore, polymer gel profile control agents are more commonly used in practical applications.

[0004] Currently, the most widely used tertiary oil recovery technology both domestically and internationally is polymer flooding (FLAG), which increases swept volume. This includes binary, ternary, and foam composite FLAG technologies, which can improve both swept volume and oil washing efficiency. Experiments and field trials have demonstrated that polymer flooding can effectively increase the swept volume of the oil reservoir, improving oilfield recovery by more than ten percentage points. However, polymer flooding has relatively high investment costs. For heterogeneous reservoirs, its poor plugging ability and limited impact on low- and medium-permeability layers lead to unsatisfactory oil displacement results. Furthermore, it is not well-suited for small fault-block oilfields and offshore oilfields with limited platform areas. Additionally, the viscosity of the polymer solution is significantly affected by reservoir temperature and salinity.

[0005] To address the aforementioned problems, research has been conducted both domestically and internationally on deep profile control and oil displacement technologies, such as: colloidal dispersion gel (CDG) profile control technology, weak gel profile control system, pre-crosslinked gel profile control technology, polymer microsphere profile control, and flexible diverting agents.

[0006] The advantages of colloidal dispersion gel (CDG) flooding technology are that, compared to other types of organic gels, it requires less polymer and crosslinking agent, resulting in lower costs; it can migrate within the formation and also has an oil displacement effect. The disadvantages of this system are that its gelation in the formation is affected by many factors such as shear, degradation, salinity, temperature, and crosslinking agent adsorption, making it prone to non-crosslinking problems; its strength is weak, making it unsuitable for sealing fractures and large pores; and the system cannot be applied to high-temperature reservoirs.

[0007] The advantage of weak gel-based profile control systems is their ability to migrate within formations, enabling deep profile control and oil displacement. However, the main problems currently are: excessively rapid cross-linking, meaning the system cross-links before penetrating deep into the formation, leading to excessively high injection pressure; or inability to gel within the formation due to formation water dilution and adsorption loss of cross-linking agent ions; and finally, high-temperature degradation of the polymer limits the system's application range.

[0008] Pre-crosslinked gel plugging technology has "amoeba" characteristics, enabling it to penetrate deep into formations and plug high-permeability layers. However, this system has several drawbacks. Pre-crosslinked gel particles absorb water rapidly, typically expanding in the surface preparation tank before being pumped into the wellbore, complicating the injection process and hindering migration to deeper formations. Furthermore, the material weakens after absorbing water, with increasingly poorer mechanical properties. During pumping, passing through screens, and migrating deeper into the formation, the material is prone to shearing and fragmentation, resulting in smaller particle sizes and ultimately losing its plugging and regulating effect. Additionally, because the material is polymerized from acrylamide monomers, it is unsuitable for use in reservoirs above 80°C.

[0009] The advantages of polymer microsphere profile control systems are good dispersibility, no need for large injection pump stations and dedicated injection pipelines, and suitability for profile control in single wells, small blocks, and offshore oilfields; the small particle size is suitable for deep profile control in low-permeability reservoirs. The disadvantages are that the small particle size makes it prone to contaminating non-target layers, and its ability to seal large pores and fractures is limited; the material is organic, making it unsuitable for high-temperature reservoirs.

[0010] Flexible diverting agents, through their own deformation and recovery, as well as a certain degree of secondary adhesion, migrate along the flow path, creating temporary blockage and pulsation phenomena. This generates dynamic flow resistance, thereby altering the water drive channel, achieving deep fluid flow diversion, and increasing the water drive swept volume. This system is unaffected by reservoir temperature and salinity, and is suitable for high-temperature, high-salinity reservoirs, especially high-permeability reservoirs with fractures. Its drawbacks include high cost, limiting its widespread adoption, and a particle size much larger than the pore throat size, thus restricting injection depth.

[0011] In summary, to achieve the goals of deep profile control and displacement, the system must meet the requirements of being able to "get in, be able to block, and be able to move." The systems mentioned above either get in but can't be blocked and can move, or they get in, can be blocked but can't move, and often have poor temperature and salt resistance. Summary of the Invention

[0012] To address the aforementioned problems in oilfield water injection development, this invention provides an adaptive mobile polymer gel profile control agent that meets the requirements of "being able to enter, being able to block, and being able to move," and has strong temperature resistance and salt resistance. It can be used for advantageous channel control in oilfield water injection development and other displacement processes, solving the problem of displacement fluid channeling.

[0013] The technical solution adopted in this invention is as follows: In a first aspect, the present invention provides a method for preparing a polymer gel profile modifier, comprising the following steps: S1. Mix methacryloylpropyltrimethylammonium chloride, dimethyldiallylammonium chloride, acrylamide, methylenebisacrylamide and water, add an initiator, and polymerize to obtain polymer A; S2. Mix 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, acrylamide, methylenebisacrylamide and water, adjust the pH of the system to neutral, add an initiator, and polymerize to obtain polymer B. S3. Pulverize and mix polymer A and polymer B, soak them in a stabilizer, and process them with a colloid mill to obtain a gel dispersion; S4. Add crosslinking agent and auxiliary agent to the obtained gel dispersion to obtain polymer gel profile modifier; In step S3, the stabilizer is a sodium chloride solution with a mass fraction of 10-30%. In step S4, the crosslinking agent is a high-valence metal ion crosslinking agent encapsulated in paraffin microcapsules prepared from zirconium oxychloride core material and semi-refined paraffin wall material.

[0014] In step S1, based on the total mass of the raw materials used to prepare polymer A, the following components are present: 10-15% methacryloylpropyltrimethylammonium chloride, 10-20% dimethyl diallyl ammonium chloride, 5-10% acrylamide, and 0.01-0.1% methylenebisacrylamide.

[0015] In step S1, the initiator may be ammonium persulfate.

[0016] In step S1, the conditions for the polymerization reaction are: temperature of 40-80℃, preferably 60℃, and time of 10-72h, preferably 48h.

[0017] In step S2, based on the total mass of the raw materials used to prepare polymer B, the mass fraction of 2-acrylamide-2-methylpropanesulfonic acid is 10-50%; the mass fraction of acrylic acid is 5-15%; the mass fraction of acrylamide is 5-10%; and the mass fraction of methylenebisacrylamide is 0.01-0.1%.

[0018] In step S2, the initiator may be ammonium persulfate. In step S2, the polymerization reaction conditions are: temperature 15-30℃, time 70-75h.

[0019] In step S3, the mass ratio of polymer A to polymer B is (1.5-2.5):1.

[0020] In step S3, the stabilizer is a sodium chloride solution with a mass fraction of 10-30%, preferably a sodium chloride solution with a mass fraction of 25%; the soaking time is 24-26 hours; and the particle size of the soaked material is pulverized to 2-100 μm, preferably 45-55 μm.

[0021] In step S4, the preparation of the crosslinking agent includes: adding a saturated zirconium oxychloride solution to molten paraffin to form a water-in-oil (W / O) dispersion; adding the resulting dispersion to an aqueous emulsifier solution to form an oil-in-water (O / W) emulsion; and cooling and solidifying the resulting emulsion to obtain the crosslinking agent. The saturated zirconium oxychloride solution is prepared by adding zirconium oxychloride and polyvinyl alcohol to water; the mass ratio of the core material zirconium oxychloride to the wall material paraffin is 1:(3-3.5); the emulsifier is composed of Span-80 and Tween-80 in a mass ratio of 4:1; the amount of emulsifier is 20-25% of the core material mass; and the amount of polyvinyl alcohol is 2-3% of the core material mass.

[0022] As a specific embodiment of the present invention, the crosslinking agent is prepared according to the following steps: (1) Molten paraffin; (2) Add zirconium oxychloride and polyvinyl alcohol to water to prepare a saturated solution of zirconium oxychloride; (3) Preheat the saturated zirconium oxychloride solution, add it to the molten paraffin, and stir at high speed to form a water-in-oil W / O dispersion; (4) The above dispersion was added to a 2% (w / w) emulsifier aqueous solution and sheared at high speed to form an oil-in-water O / W emulsion; (5) Cool and solidify, wash with water to remove residual zirconium oxychloride on the surface to obtain a crosslinking agent.

[0023] In step S4, the additives are cationic polyacrylamide and sodium polyacrylate; based on the mass of the gel dispersion, the amount of crosslinking agent added is 0.05-0.15%, the amount of cationic polyacrylamide added is 0.1-0.2%, and the amount of sodium polyacrylate added is 0.1-0.2%.

[0024] Secondly, the present invention provides a polymer gel profile modifier obtained by the preparation method described above.

[0025] Thirdly, the present invention provides the application of the polymer gel profile control agent in the field of oilfield development.

[0026] Compared with the prior art, the beneficial effects achieved by the present invention are: The adaptive mobile polymer gel profile control agent provided by this invention has the following advantages: (1) Adaptive mobility (selectivity): This invention uses high-concentration sodium chloride as a protective liquid, which restricts the effects of hydrogen bonds and ionic bonds. At the same time, it uses zirconium oxychloride encapsulated in paraffin microcapsules as a crosslinking agent to ensure that it can only be released at temperatures above 55°C, avoiding premature crosslinking. This ensures that the gel will preferentially and selectively enter the dominant channel after being injected into the formation. As the subsequent water injection washes over the formation, the high-concentration protective liquid is diluted, and the formation temperature dissolves the paraffin capsules. The gel gradually forms gel particles and colloids, which play a role in selectively blocking the dominant channel. At the same time, as the pressure increases, the gel will break through and migrate in the dominant channel. Due to the excellent shear resistance of the gel, it will form a secondary gel at the front end and block again, thus realizing a cycle of blocking-breakthrough migration-re-blocking. This is a brand-new oil displacement and plugging mode, which realizes full-process profile control of the oil layer. It has been applied in multiple oilfields such as Xinjiang, Liaohe, Changqing, Jilin, and Qinghai for water injection, foam flooding and other dominant channel control, and has achieved good oil increase and water reduction effects.

[0027] (2) Shear resistance: The polymer gel profile control agent of the present invention has a self-healing function after shearing through the ion adsorption of cationic and anionic groups, the hydrogen bond formed by amide groups, and the cross-linking effect of high-valence metal ions zirconium. This enables the movable sealing function.

[0028] (3) Temperature resistance: By introducing sulfonic acid groups and other groups, and reducing the amount of acrylamide, the present invention significantly improves the temperature resistance (greater than 150°C) of the polymer gel profile control agent, making it suitable for most oil reservoirs.

[0029] (4) Salt resistance: In addition to crosslinking, the zirconium oxychloride in this invention can also improve the salt resistance of the gel. It can still form a gel when rinsed with high-salt injection water (such as injection water in Qinghai with a mineralization of more than 170,000 mg / L), making it more adaptable.

[0030] (5) Good injectability: The gel has small particle size and low viscosity, making it easy to inject. It can be applied all year round without seasonal restrictions.

[0031] (6) Convenient construction: The present invention is constructed by slug method, which is relatively simple and completely solves the problems of complicated preparation of commonly used polyacrylamide gel, long construction period and inability to construct in winter.

[0032] In summary, the polymer gel profile control agent provided by this invention is applicable to improving oil recovery in high water-cut oilfields, fault-block oilfields, and offshore oilfields. It is a new technology for improving oil recovery that is easy to inject, has diverse combinations, strong adaptability, high sweep efficiency, and low injection cost, and is of great significance to the later-stage development of oilfields. Attached Figure Description

[0033] Figure 1 This is a displacement test simulation device.

[0034] Figure 2 Pressure changes during the displacement test pressure transmission experiment of the gel profile control agent prepared in Example 1.

[0035] Figure 3 The pressure change in the displacement test pressure transmission experiment using a non-moving gel.

[0036] Figure 4 Photographs of shear tests on the gel profile control agent prepared in Example 1.

[0037] Figure 5 Photographs showing the sweep area of ​​the gel profile control agent prepared in Example 1.

[0038] Figure 6 Photographs of the temperature resistance and mineralization resistance test of the gel profile control agent prepared in Example 1.

[0039] Figure 7 Production curve of the gel profile control agent prepared in Example 1 after profile control in well SN8201 of the oilfield.

[0040] Figure 8 Production curve of the gel profile control agent prepared in Example 1 after profile control in well SN8203 of the oilfield. Detailed Implementation

[0041] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0042] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0043] Unless otherwise specified, all reagents, materials, instruments, etc. used in the following examples are commercially available.

[0044] The monomers used in the following examples were all purchased from Jiangsu Fumiao Technology Co., Ltd.

[0045] Methacrylpropyltrimethylammonium chloride: CAS Registry No. 51410-72-1.

[0046] Dimethyl diallyl ammonium chloride: CAS Registry No. 7398-69-8, belongs to a cationic polyquaternary ammonium salt.

[0047] 2-Acrylamide-2-methylpropanesulfonic acid: CAS Registry No. 15214-89-8.

[0048] The high-valence metal ion crosslinking agent used in the following examples, which is encapsulated in paraffin microcapsules, is a self-made material, consisting of 20g of zirconium oxychloride core material, 60g of semi-refined paraffin wax at 65-75℃ wall material, 4g of emulsifier (Span-80: Tween-80 mass ratio of 8:2), and 0.5g of polyvinyl alcohol stabilizer.

[0049] The specific preparation steps are as follows: (1) Molten paraffin; (2) Add zirconium oxychloride and stabilizer polyvinyl alcohol to water to prepare a saturated solution of zirconium oxychloride; (3) Preheat the saturated zirconium oxychloride solution, add it to the molten paraffin, and stir at high speed to form a water-in-oil W / O dispersion; (4) The above dispersion was added to a 2% (w / w) emulsifier aqueous solution and sheared at high speed to form an oil-in-water O / W emulsion; (5) Cool and solidify, wash with water to remove residual zirconium oxychloride on the surface to obtain a crosslinking agent.

[0050] Example 1

[0051] This embodiment provides a preparation method for a polymer gel profile control agent, and the specific steps are as follows: (1) Based on the total mass of the raw materials for preparing polymer A, 10% of methacryloylpropyltrimethylammonium chloride, 15% of dimethyl diallyl ammonium chloride, 5% of acrylamide, 0.1% of methylenebisacrylamide, and the remainder being pure water are mixed evenly; then 0.1% of ammonium persulfate initiator is added, and polymerization is carried out at 60°C for 48 hours to obtain polymer A.

[0052] (2) Based on the total mass of the raw materials for preparing polymer B, 20% of 2-acrylamide-2-methylpropanesulfonic acid, 10% of acrylic acid, 5% of acrylamide, 0.1% of methylenebisacrylamide, and the remainder being pure water were mixed evenly; sodium hydroxide was added to neutralize (system pH = 7), and 0.1% of ammonium persulfate was added as initiator. Polymerization was carried out at room temperature for 72 hours to obtain polymer B.

[0053] (3) The polymer A: polymer B = 2:1 (mass ratio) is crushed and mixed, soaked in a 25% sodium chloride solution for 24 hours, and then crushed to about 50 μm using a colloid mill to obtain a gel dispersion. (4) Based on the mass of the gel dispersion, add 0.1% of the crosslinking agent zirconium oxychloride coated with paraffin microcapsules, 0.15% of the auxiliary agent cationic polyacrylamide, and 0.1% of the auxiliary agent sodium polyacrylate to the gel dispersion and mix to obtain the polymer gel profile modifier.

[0054] All the following tests were conducted using the polymer gel profile modifier prepared in Example 1.

[0055] 1. Displacement test pressure transmission status: like Figure 1 As shown, in the simulation device, a horizontal flow pump is used for driving, a six-way valve is used to control the injection of working fluid, the sand-filling pipe is 1 meter long, and a pressure sensor is set every 25 cm and connected to a paperless recorder to record pressure changes.

[0056] The experimental procedure is as follows: The polymer gel profile control agent prepared in Example 1 was injected into the sand-filled tube using a slug injection method. After injecting one slug, a release agent was injected, followed by water, and this process was repeated. The pressure changes at different locations were observed. In the obtained pressure curve, red, green, blue, and yellow represent the pressure values ​​of pressure sensors 1, 2, 3, and 4, respectively.

[0057] Meanwhile, the non-moving gel water glass and calcium chloride two-liquid method was used as a control example; in this method, by mass fraction, the water glass with a modulus of 3.2 was 8%, the calcium chloride was 9%, and the separating liquid was water.

[0058] The experimental results are as follows: (1) such as Figure 2 As shown, after the first septum plug is inserted, water is injected. As the gel system gradually forms a gel, the pressure rises slowly, and there will be pressure fluctuations in the early stages. After the pressure gradually stabilizes, the second septum plug is inserted, and water is injected again, and the pressure will gradually increase. The pressure value represents the sealing capacity. The more septum plugs there are, the higher the sealing pressure and the stronger the sealing capacity.

[0059] (2) such as Figure 3 As shown, pressure is not transmitted after using non-moving gel, resulting in blockage, and the pressure curve only shows red values.

[0060] 2. Shear resistance like Figure 4 As shown, the gel prepared in Example 1 can be gelled again after high-speed shearing, exhibiting good shear resistance.

[0061] 3. The effect of gel on the swept area Planar models are a key indicator for evaluating the effectiveness of profile adjustment.

[0062] Test results: such as Figure 5As shown, 1 represents medium permeability, 2 represents ultra-high permeability, 3 represents low permeability, and 4 represents high permeability. Red represents simulated oil. After water injection, the ultra-high permeability layer 2 protrudes. After profile adjustment, water injection spreads in the 1 / 2 / 4 directions. Then, water injection expands the spread volume, with a significant increase in the spread volume in the 1 / 2 / 4 directions. Further, the spread volume continues to expand, with a significant increase in the spread volume in the 2 / 4 direction and a breakthrough in the 1 direction. Finally, the 2 / 4 direction is fully affected, the spread volume in the 1 direction expands, and the remaining oil in the 3 direction is activated.

[0063] 4. Convenient construction The adaptive mobile gel provided by this invention is applied using a slug method, which is relatively simple; moreover, the gel has a small particle size, low viscosity, and is easy to inject, allowing for year-round application. In contrast, commonly used polyacrylamide gels have complex preparation processes, long application cycles, and cannot be applied in winter.

[0064] 5. Temperature resistance and mineralization resistance like Figure 6 As shown, the adaptive mobile gel provided by this invention can be applied at temperatures above 150°C and has a mineralization of 200,000 mg / L or higher (after aging at 150°C and 200,000 mg / L for 72 hours, the gel shows no change), and can be used to improve oil recovery in high-temperature and high-mineralization oilfields.

[0065] 6. Actual oilfield application effects The adaptive mobile gel described in this invention was used to increase oil production in different well groups in the Shixi Oilfield of Karamay, Xinjiang.

[0066] like Figure 7 As shown, the SN8201 well was subjected to a booster operation on May 4, 2017. The well group consists of 8 oil wells, and as of May 2018, it has generated a cumulative increase of 4,384 tons of oil, with significant results.

[0067] like Figure 8 As shown, the SN8203 well was subjected to a booster operation on July 12, 2017. The well group consists of 9 oil wells, and as of May 2018, it has generated a cumulative increase of 2,713 tons of oil, with significant results.

[0068] As shown in Table 1, significant results were achieved by increasing oil production at different well numbers.

[0069] Table 1. Oil Increase Statistics of Shinan 31 Regulator (5 Well Groups)

[0070] Comparative Example 1 The difference from Example 1 is that no crosslinking agent is added in step (4).

[0071] The tests conducted according to the above methods showed that gelation deteriorated under high salt conditions, indicating that zirconium oxychloride encapsulated in paraffin microcapsules helps improve the salt resistance of the gel.

[0072] Comparative Example 2 The difference from Example 1 is that sodium polyacrylate and cationic polyacrylamide are not added in step (4).

[0073] The tests conducted according to the above methods showed that the gel micelles dispersed, indicating that the additives sodium polyacrylate and cationic polyacrylamide can improve the stability of the gel.

[0074] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a polymer gel profile modifier, characterized in that, Includes the following steps: S1. Mix methacryloylpropyltrimethylammonium chloride, dimethyldiallylammonium chloride, acrylamide, methylenebisacrylamide and water, add an initiator, and polymerize to obtain polymer A; S2. Mix 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, acrylamide, methylenebisacrylamide and water, adjust the pH of the system to neutral, add an initiator, and polymerize to obtain polymer B. S3. Pulverize and mix polymer A and polymer B, soak them in a stabilizer, and process them with a colloid mill to obtain a gel dispersion; S4. Add crosslinking agent and auxiliary agent to the obtained gel dispersion to obtain polymer gel profile modifier; In step S3, the stabilizer is a sodium chloride solution with a mass fraction of 10-30%; In step S4, the crosslinking agent is a high-valence metal ion crosslinking agent encapsulated in paraffin microcapsules prepared from zirconium oxychloride core material and semi-refined paraffin wall material.

2. The preparation method according to claim 1, characterized in that, In step S1, based on the total mass of the raw materials used to prepare polymer A, the following components are present: 10-15% methacryloylpropyltrimethylammonium chloride, 10-20% dimethyl diallyl ammonium chloride, 5-10% acrylamide, and 0.01-0.1% methylenebisacrylamide.

3. The preparation method according to claim 1, characterized in that, In step S1, the conditions for the polymerization reaction are: temperature of 40-80℃ and time of 10-72h.

4. The preparation method according to claim 1, characterized in that, In step S2, based on the total mass of the raw materials used to prepare polymer B, the mass fraction of 2-acrylamide-2-methylpropanesulfonic acid is 10-50%; the mass fraction of acrylic acid is 5-15%; the mass fraction of acrylamide is 5-10%; and the mass fraction of methylenebisacrylamide is 0.01-0.1%.

5. The preparation method according to claim 1, characterized in that, In step S2, the polymerization reaction conditions are: temperature 15-30℃ and time 70-75h.

6. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of polymer A to polymer B is (1.5-2.5):1; The soaking time is 24-26 hours; The particle size of the soaked material is pulverized to 2-100 μm.

7. The preparation method according to claim 1, characterized in that, In step S4, the preparation of the crosslinking agent includes: adding a saturated solution of zirconium oxychloride to molten paraffin to form a water-in-oil (W / O) dispersion; adding the obtained dispersion to an aqueous emulsifier solution to form an oil-in-water (O / W) emulsion; and cooling and solidifying the obtained emulsion to obtain the crosslinking agent.

8. The preparation method according to claim 1, characterized in that, In step S4, the auxiliary agent is cationic polyacrylamide and sodium polyacrylate; Based on the mass of the gel dispersion, the amount of crosslinking agent added is 0.05-0.15%, the amount of cationic polyacrylamide added is 0.1-0.2%, and the amount of sodium polyacrylate added is 0.1-0.2%.

9. The polymer gel profile control agent obtained by the preparation method according to any one of claims 1-8.

10. The application of the polymer gel profile control agent according to claim 9 in the field of oilfield development.

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